Common subdirectories: xinit.orig/privileged_startx and xinit/privileged_startx
diff -u xinit.orig/startx.cpp xinit/startx.cpp
--- xinit.orig/startx.cpp	2011-08-02 18:26:57.161711018 +0400
+++ xinit/startx.cpp	2011-08-02 19:06:39.348816866 +0400
@@ -290,9 +290,9 @@
     XCOMM now add the same credentials to the client authority file
     XCOMM if '$displayname' already exists do not overwrite it as another
     XCOMM server man need it. Add them to the '$xserverauthfile' instead.
-    for displayname in $authdisplay $hostname$authdisplay; do
+    for displayname in $authdisplay $hostname/unix$authdisplay; do
         authcookie=`XAUTH list "$displayname" @@
-        | sed -n "s/.*$displayname[[:space:]*].*[[:space:]*]//p"` 2>/dev/null;
+        | sed -n "s/.*$hostname\/unix$authdisplay[[:space:]*].*[[:space:]*]//p"` 2>/dev/null;
         if [ "z${authcookie}" = "z" ] ; then
             XAUTH -q << EOF 
 add $displayname . $mcookie
